The human brain is driven, in large part, by its need to assess plans: providing motivation to act on good plans, and reducing motivation (which we experience as procrastination) to act on flawed plans.
When the specific plan fails, the resulting lack of motivation infects the general goal as well.
You can’t force your brain to generate motivation. It will do so only when it believes in both your goal and your plan for accomplishing the goal.
If you find that you’re still failing to get work done, even when you’re more flexible with your scheduling, the problem is not your productivity, it’s instead that your mind is not yet sold that you know how to succeed with your general goal.
Your mind requires a reality-based understanding of your goal in addition to achievable short-term plans.
To leverage the psychology of your brain, you need to instead choose clear goals that you clearly know how to accomplish, and then approach scheduling with flexibility. Be aggressive, but remain grounded in the reality of your schedule. If your mind thinks you have a good goal and sees your short terms plans are working, it will keep you motivated toward completion.